Fire & Safety ●From previous page
increasingly these are being superseded by wireless technology. At the same time, mains- powered alarms are giving way to battery-powered alarms that are able to last for a decade.
These wireless networks offer the same benefits of hard-wired alarms, in that when one goes off all of the other alarms on the network follow suit. Up to 50 alarms can be interlinked in a single wireless network. Each alarm then communicates with others by continuously sending and receiving wireless signals to constantly monitor and communicate with the network.
When any alarm detects smoke, heat or CO the wireless module inside sends a signal to all the connected alarms to ensure a fast reaction across the network.
A useful function in wireless networks is the ability to press the test/reset button on any alarm in the network and silence all but the initiating alarm that sensed the smoke, heat or CO.
A major benefit of using a wireless protection system is that the network can be established very quickly, just a few seconds to follow a simple connection process, and it is very easy to add and remove different devices. For example, if a rented property is equipped with a wireless protection system then it can be easily and cost-effectively reconfigured to suit the assisted living requirements of individual tenants.
Sensor selection
A protection network of this nature can incorporate up to three different types of sensor: smoke, heat and CO. With smoke alarms it is important to
Another issue for wholesalers to consider is how the various devices interact with
each other. Historically this would have been achieved through hard-wired networks but
increasingly these are being superseded by wireless technology.
choose the most appropriate sensing technology; in our view this is one that combines optical sensing technology with thermal enhancement to provide a swift reaction to both fast-flaming and slow smouldering fires in a single alarm. Ideally the detector should constantly monitor for temperature change so that if a rate of temperature rise is detected, the sensitivity of the alarm is increased to provide a quicker response time to both types of danger. Heat alarms are designed for areas where dust and fumes may trigger frequent nuisance alarms in conventional smoke alarms, making them ideal for attics, garages and kitchens. Typically, a heat alarm will activate when the temperature reaches a pre- set range between 54°C and 65°C. This should be combined with constant monitoring for temperature change so that if
the temperature is predicted to exceed an alarm trigger threshold, the alarm will sound. Use of a radiant heat dish to reflect heat from a fire onto the thermistor will improve reaction time.
A carbon monoxide alarm uses
electrochemical sensors to measure levels of carbon monoxide. It should also maintain a log of alarm events, along with CO levels at the time of the alarm, so that causes can be more easily identified.
Combined or stand-alone The other issue that customers may ask about is whether to buy separate smoke and CO alarms or whether to use one of the combined units that are now available. Clearly a combined unit offers certain benefits in terms of cost and installation however it’s important to be aware that smoke and CO pose very different threats. The best response to a CO alert is to open the windows to ventilate the room. If there is a fire, though, opening the windows will simply fuel it.
With such a wide range of requirements to address, the key for wholesalers is to ensure they stock a comprehensive range of devices and understand the application of each. In this way, they can provide customers with the most appropriate advice and potentially help to save lives.
http://sprueaegis.co.uk/ SprueSafetyProducts
32 | electrical wholesaler August 2015
www.ewnews.co.uk
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